accretion disk


variants or less commonly accretion disc
plural accretion disks also accretion discs
: a disk of usually gaseous matter surrounding a massive celestial object (such as a black hole) in which the matter gradually spirals in toward and accretes onto the object as a result of gravitational attraction
Evans' team studied a supermassive black hole with jets 800 million light-years away named 3C 33. They never found an expected X-ray pattern … which results from light reflecting off the accretion disk.Bill Andrews
Most other moons are either captured planetesimals, or they formed along with the planet in a common accretion disc.Daniel Herwartz, et al.

Example Sentences

Recent Examples on the Web The emitted X-rays can sometimes reflect off the accretion disk, creating ‘echoes’ of the initial emission. Jennifer Ouellette, Ars Technica, 2 May 2022 These are called relativistic jets, and they're made of superheated plasma ejected from the accretion disk. Nathaniel Scharping, Discover Magazine, 5 Apr. 2019 Rather, its energy comes from the radiation released by shockwaves on the surface of the protostar and its accretion disk. Jennifer Ouellette, Ars Technica, 16 Nov. 2022 Most material in the accretion disk eventually ends up in the black hole. Alison Klesman, Discover Magazine, 7 Apr. 2020 Material that falls toward a black hole first forms a flattened accretion disk orbiting around it. Phil Plait, Scientific American, 20 Dec. 2022 Some of that light hits the accretion disk, which absorbs it, heats up, and then emits light of its own. Alison Klesman, Discover Magazine, 5 Feb. 2019 Next up, there's the cloud of dust and gas itself, called an accretion disk. Nathaniel Scharping, Discover Magazine, 5 Apr. 2019 The material is then collected into an accretion disk that feeds a central protostar, according to NASA. Misty Severi, Washington Examiner, 12 Jan. 2023 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'accretion disk.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

First Known Use

1972, in the meaning defined above

Time Traveler
The first known use of accretion disk was in 1972

Dictionary Entries Near accretion disk

Cite this Entry

“Accretion disk.” Dictionary, Merriam-Webster, Accessed 24 Mar. 2023.

More from Merriam-Webster on accretion disk

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

What Did You Just Call Me?

  • brown chihuahua sitting on the floor with squinting eyes looking at the camera
  • Before we went to her house, Hannah told us her aunt was a flibbertigibbet.
True or False

Test your knowledge - and maybe learn something along the way.

Solve today's spelling word game by finding as many words as you can with using just 7 letters. Longer words score more points.

Can you make 12 words with 7 letters?